Article excerpt

The past 20 years have seen research on language acquisition in the cognitive sciences grow immensely. The current paper offers a fairly extensive review of this literature, arguing that new cognitive theories and empirical data are perfectly consistent with core predictions a behavior analytic approach makes about language development. The review focuses on important examples of productive linguistic behavior: word learning and early grammatical behavior. Language experience, through social and other contingencies, influences language development directly. Through these contingencies, the structure of language behavior exhibits a gradual emergence.

The modern mainstream study of language acquisition has a surprising quality. Despite decades of intense effort collecting observational and experimental facts, debate still rages as to the nature of the language learning child, and perhaps even the nature of language itself. This is somehow made more surprising when we consider the billions of in -home "laboratories" around the world permitting ever-present observation of a child's development. Indeed, language researchers themselves doubtless diligently observe the growth of language in their own children (e.g., Tomasello, 1992). Nevertheless, these observations provide a stark portrait of the debate on language learning: Even given intense observation, individual observers can differ wildly on appropriate theoretical interpretations.

There is, however, one very important consensus among most developmental psycholinguists: There is no substantial explicit negative feedback about grammar in language directed to children. An example of such feedback is presented below, and has two important properties that should be borne in mind. First, the mother must stop the flow of conversation to address the child's error, and secondly, the mother is providing information about language structure in particular - the conversation has ceased to be about the topic of discussion, but instead about the grammaticality of the child's utterance.

Child: Mummy I have toy!

Mother: No, say, "I have a toy."

Brown and Hanlon (1970) famously demonstrated in the Adam, Eve, and Sarah mother-child interaction corpora that parents do not offer such information. In tracing the development of complex sentence types in language production by children, Brown and Hanlon sought the basis on which children establish correct usage of these sentences. They discovered that information based on explicit approval and disapproval is extremely rare. The feedback they did isolate was directed towards semantic and phonological problems, with morphological and syntactic errors almost never eliciting it. Driven by early results such as these, many were eager to identify child-directed speech as altogether chaotic: "A record of natural speech will show numerous false starts, deviations from rules, changes of plan in midcourse, and so on." (Chomsky, 1965, p. 4) This famous quote exemplifies an ideological momentum at that time to characterize the child's task as rife with difficulty and void of a certain "linguistic pedagogy" that behaviorist theories supposedly required. To this day, linguistics textbooks are persistent in presenting this tendency (e.g., Fromkin & Rodman, 1997; see Schlinger, 1995, p. 179 for relevant discussion). Even if it were present, some argued, a number of famous anecdotal examples supposedly demonstrate that children might not use it to change their language anyway: